FN4A-EL, 4F27E

Symptoms:

• Clutch & band failures
• Loss of lube oil
• Low line pressure
• High line pressure
• Soft shifts
• Harsh shifts
• Low converter pressure

Cause:
Continuous oscillation of pressure regulator valve results in excess bore wear, causing erratic line pressure and/or restricting converter feed oil.

Correction:
Recover hydraulic control and renew line pressure performance by reconditioning the bore and installing Sonnax oversized pressure regulator valve kit.

Warning:
Follow the OE recommended torque sequence and amounts to prevent sticking of the pressure regulator valve.

Ford/Mazda 4F27E, FN4A-EL, FNR5 and FS5A-EL units may exhibit multiple line pressure and converter-related problems due to excess wear in the pressure regulator bore. Wear at the balance spool end allows critical fluid loss, resulting in high line pressure, harsh shifts, and overheating due to reduced cooler/converter/lube flow. Wear at the outboard spool area robs converter feed pressure and lowers line pressure, causing soft shifts and burnt clutches and bands.

Reconditioning the bore and installing Sonnax oversized pressure regulator valve kit restores hydraulic integrity for proper line pressure control in all ranges. The hardcoat anodized aluminum valve combats premature wear

Content:

• End Plug (Ford only)
• Valve

SONNAX Installation Instructions